Crynodeb

Background: Research on wild animal ecology is increasingly employing GPS telemetry in order to determine
animal movement. However, GPS systems record position intermittently, providing no information on latent
position or track tortuosity. High frequency GPS have high power requirements, which necessitates large batteries
(often effectively precluding their use on small animals) or reduced deployment duration. Dead-reckoning is an
alternative approach which has the potential to ‘fill in the gaps’ between less resolute forms of telemetry without
incurring the power costs. However, although this method has been used in aquatic environments, no explicit
demonstration of terrestrial dead-reckoning has been presented.
Results: We perform a simple validation experiment to assess the rate of error accumulation in terrestrial deadreckoning.
In addition, examples of successful implementation of dead-reckoning are given using data from the
domestic dog Canus lupus, horse Equus ferus, cow Bos taurus and wild badger Meles meles.
Conclusions: This study documents how terrestrial dead-reckoning can be undertaken, describing derivation of
heading from tri-axial accelerometer and tri-axial magnetometer data, correction for hard and soft iron distortions
on the magnetometer output, and presenting a novel correction procedure to marry dead-reckoned paths to
ground-truthed positions. This study is the first explicit demonstration of terrestrial dead-reckoning, which provides
a workable method of deriving the paths of animals on a step-by-step scale. The wider implications of this method
for the understanding of animal movement ecology are discussed.
Keywords: Step length, dead reckoning, animal movement, GPS, terrestrial